Aerosol dispensing containers generally comprise a pressurized canister within which is stored a product to be dispensed as an aerosol. The canister is pressurized, for example, by a propellant which may be dissolved within the product. The product is released from the canister upon opening of a valve mechanism.
The valve mechanism generally comprises a valve stem having a passage therein through which product may flow. An orifice is provided in the wall of the valve stem to provide access to the passage. The valve stem is normally biassed to a position in which the orifice is blocked or sealed, so that product cannot enter the passage in the valve stem. A valve actuation assembly is fixedly mounted on the canister to overly the valve stem. When the actuation assembly is appropriately triggered, the valve actuation assembly depresses or tilts the valve stem against the biassing force to unblock the orifice and allow the pressurized product within the canister to enter the passage in the valve stem.
Typically, the actuator assembly includes a housing fixed to the canister and an actuator plunger within the housing. The plunger fits over the valve stem so that the passage in the valve stem communicates with a passage in the plunger. The plunger is frictionally fitted to the valve stem to retain the plunger thereon. The plunger passage terminates at a dispensing orifice or nozzle. Thus, when the plunger is depressed by a user, the valve stem is also depressed. As the valve stem is depressed, the orifice within the valve stem is moved away from the seal, and the pressure within the canister pushes product up through the orifice and the passage in the valve stem, through the actuator plunger passage, and out the dispensing orifice in the actuator plunger. After dispensing the desired amount of product, the plunger is released. A spring within the valve mechanism provides the restoring or biassing force to return the valve stem to the closed position in which the orifice is sealed. FIGS. 1 through 4 illustrate a typical prior art actuation mechanism of this type.
To prevent accidental discharge of product from the canister, as illustrated in FIGS. 3 and 4, the actuation plunger may be rotatable about the longitudinal axis of the container to a safety position in which a tab or handle portion on the plunger is moved over a shoulder located on the actuator housing, thereby preventing the plunger from being depressed. Rotation of the actuation plunger also turns the dispensing orifice to a position against the actuator housing to further prevent discharge of the contents of the canister.
As set forth above, the actuation plunger is frictionally fitted over the valve stem to prevent the plunger from falling off. However, several disadvantages arise from use of a friction fit of the plunger to the valve stem. The plunger is typically manufactured from a thermoplastic material, such as polyethylene or polypropylene, by an injection molding process. Thermoplastics are subject to expansion and contraction as the temperature changes, and it is difficult to control the final dimensions of an injection molded piece as the plastic cools. As a result, it is difficult to achieve a tolerance of, for example, .+-.0,002 inch, which is the desired tolerance to ensure a proper friction fit between the plunger and the valve stem.
Accordingly, the friction fit is not always reliable. The plunger may fall off in spite of the friction fit or in response to other forces. For example, canisters of this nature are typically used to contain pepper gas, a self-defense product. Such canisters are carried in purses or pockets where other items frequently bang the plunger to rotate it out of the safety position and wedge or pull the plunger off. The exposed valve stem is then subject to depression and accidental firing by further jostling or banging. Additionally, the orifice of the valve stem can frequently be unblocked merely by tilting the valve stem. In this case, tilting or other movements of the plunger, even if the plunger is in the safety position, may concomitantly cause tilting of the valve stem and flow of product into the valve stem passage. The product in the passage can then leak out, either through the nozzle and down the inside of the housing, or around the friction fit between the plunger and valve stem, since the friction fit may not provide an adequate seal. In any case, the product is wasted and creates an undesirable mess inside a purse or pocket.
A further disadvantage of the friction fit arises during manufacture of the container. The valve actuation assembly is generally attached to the canister after the valve mechanism has been attached and the canister charged with pressurized product. Thus, depression of the valve stem would cause release of product. However, in frictionally fitting the plunger of the valve actuation assembly over the valve stem, the valve stem is subject to depression and, in practice, frequently is depressed, resulting in discharge of product. The discharged product again creates a mess and over a period of time the wasted product can give rise to significant economic losses.
Several variations of the actuator described above are found in the prior art. U.S. Pat. No. 3,848,778 to Meshberg discloses an actuation plunger that is rotatable between a dispensing position and a nondispensing or safety position in which the discharge orifice is blocked by a wall. The actuation plunger is locked in the nondispensing position by a tongue or key on a flexible tab of the actuator housing which is received in a corresponding slot or groove in the actuation plunger. However, to unlock the actuation plunger, the flexible tab must be moved radially outwardly by the fingernail of one hand while the plunger is rotated by the other hand.
U.S. Pat. No. 3,325,054 to Braun discloses an aerosol valve employing a complex arrangement in which stop lugs are formed on the valve button to prevent it from being depressed until the valve button is rotated to align the stop lugs with correspondingly shaped cutouts in a valve button lock. Downwardly depending fingers on the button retain the button on the lock.
U.S. Pat. No. 3,608,791 to Jordan et al. discloses an actuator assembly that includes a rotatable actuator button mounted within a cap member. A vertically oriented ridge on the button engages one of a pair of corresponding notches to hold the button in either a dispensing position or a nondispensing position in which the spout engages a stepped surface to prevent depression. The button is retained on the valve stem by friction. U.S. Pat. No. 3,249,260 to Goldberg discloses an actuator assembly that includes a rotatable lid with a spout thereon concentrically mounted in a support member. The spout possesses a bead which engages a groove on an upper step of the support member when the lid is rotated to prevent actuation. U.S. Pat. No. 3,185,350 to Abplanalp et al. also shows a rotatable actuator which can be raised and rotated over a camming member to prevent depression thereof and discharge of product. The actuator is tightly fitted to the valve stem to be movable therewith.
These variations of the actuator mechanism do not address all of the shortcomings identified above, however. A need still exists for an actuator mechanism that is simple to manufacture by injection molding, that can be installed on the valve assembly without causing accidental firing and discharge of product, that can be retained in a safety position on the canister, yet can be easily and quickly returned to the operative position, that prevents leakage, and that is not subject to accidental firing even in the safety position.